Study of C₆₀ transport in porous media and the effect of sorbed C₆₀ on naphthalene transport

Abstract

In this study, the transport of water-stable “nano-C60 particles” (a term used to refer to underivatized C60 crystalline nanoparticles, stable in water for months) through a soil column (packed with Lula soil, 0.27% organic carbon) was investigated for the first time. Nano-C60 particle breakthrough experiments were conducted at different flow rates, while other column operating parameters remained fixed through all the experiments. Nano-C60 particles were observed to be more mobile at higher flow velocity: at the flow velocity of 0.38 m/d, the maximum percent of nano-C60 breakthrough (C/C0) was 47%; at the flow velocity of 3.8 m/d, the plateau value of nano-C60 breakthrough was 60%; and at the flow velocity of 11.4 m/d, the plateau value of nano-C60 breakthrough was almost 80%. At the low flow velocity (0.38 m/d), which is typical of groundwater flow, nano-C60 particles showed very limited mobility: after about 57 pore volumes, they deposited to the soil column so rapidly that virtually no nano-C60 was detected in the effluent. This observed “favorable deposition” (attachment efficiency α = 1) was probably due to “filter ripening.” Also the release of nano-C60 particles after flow interruption was observed. The transport of naphthalene through the same soil column containing 0.18% nano-C60 particles deposited was measured. A retardation factor of about 13 was observed, possibly suggesting that sorbed nano-C60 particles in the soil column sorbed naphthalene similar to soil organic carbon. An asymmetric naphthalene breakthrough curve was observed, which is possibly due to “sorption nonequilibrium.”

Emerging patterns for engineered nanomaterials in the environment: a review of fate and toxicity studies

“…A low flow rate reduces ENM transport due to increased probability of collision, whereas a higher flow rate increases mobility in part due to the reduced likelihood of attachment (Ben-Moshe et al 2010;Jeong and Kim 2009). For example, at the low flow velocity typical of groundwater (0.38 m/day), C 60 NPs showed limited mobility (Cheng et al 2005). However, another study determined that while doubling the flow velocity did increase the transport of TiO 2 , this increase was not significant (Godinez and Darnault 2011).…”

Instrumental approach toward understanding nano-pollutants

“…In another study, the mobility of fullerenes (n-C 60 ) through the soil with high water flow was investigated. The results showed that the interaction between n-C 60 and the porous media was reduced due to the increase of water flow [22]. So far, there have been very few relevant studies on the aqueous stability and the aggregation of NPs in the environment.…”

Microchemical contaminants as forming agents of anthropogenic soils

“…For example, Cheng et al (2005) reported that the retention of naphthalene in soil was affected by C 60 presence. In a column experiment, C 60 was added to a Lula silty loam soil (Pennsylvania, USA) and its retention was determined following naphthalene application.…”